This application claims the priority of German application 198 60 201.4, filed Dec. 24, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an arrangement for the spinning of yarn or thread from a plurality of yarn components, comprising
a drafting arrangement comprising a front roller pair feeding at least two yarn components, PA1 a condensing zone downstream thereof through which all yarn components travel, PA1 a stationary sliding surface provided in the condensing zone, which sliding surface comprises at least one suction slit which extends essentially in transport direction of the yarn components, PA1 a perforated transport belt which transports the yarn components over the sliding surface, PA1 a nipping roller defining the condensing zone on an exiting side by forming a nipping point, PA1 and a ring spindle downstream thereof which twists all yarn components jointly.
An arrangement of this type is prior art in the international patent application WO 98/39505. Two fiber rovings are drafted in the drafting arrangement at close proximity to one another and thereafter condensed downstream of the drafting arrangement in the condensing zone. Subsequently, the drafted and condensed rovings can be fed to different ring spindles or to one common ring spindle. In the latter case, a so-called mock twist occurs. The transporting belt comprises two rows of holes, of which each one guides a fiber roving through the condensing zone. The end of the condensing zone is defined by a delivery roller pair, the transport belt being looped around one of the rollers.
A previously drafted but still twist-free fiber strand is bundled in the condensing zone, so that when it exits out of the condensing zone, that is at the last nipping point, a spinning triangle does not occur when the yarn components are subsequently twisted to form a yarn. The yarn is then less hairy and has an increased evenness and a greater tensile strength. As a result of a delivery roller pair being arranged downstream of the condensing zone, the suctioning of the yarn components to be condensed ends at a significant distance from the nipping point of the delivery roller pair. The condensed yarn components have thus disadvantageously the opportunity to expand again. Thus the actual aim of the condensing zone is only partially achieved.
It is an object of the invention to design the condensing zone arranged downstream of the front roller pair of the drafting arrangement, in particular when a plurality of yarn components are present, in such a way that the condensed yarn components retain their state until they reach the nipping point.
This object has been achieved in accordance with the present invention in that the nipping roller presses the yarn components and the transport belt to the sliding surface and in that the at least one suction slit extends up to the nipping point.
The nipping roller defining the condensing zone on its exit side no longer forms the nipping point with another roller, but rather with a stationary sliding surface, over which the transport belt is slidingly guided. The at least one suction slit can thus be extended to the end of the condensing zone, so that the condensing effect is not lost before the yarns reach the nipping point. The condensed effect is particularly homogenous when the transport belt is designed as a close-meshed woven belt.
The yarn components which are twisted together to form a yarn at the ring spindle can be of varying kinds.
For example, as in the above mentioned prior art, two fiber rovings can be guided each over one suction slit and are each condensed in the condensing zone before they are united at a yarn guide downstream of the nipping point. Slivers or rovings may be involved. Additionally, a core yarn can be added, which is fed by means of a feed roller arranged at the front roller pair of the drafting arrangement. Alternatively it is possible to guide only one sliver or roving through the condensing zone and to unite it with one single core yarn.
The yarn to be twisted at the ring spindle can thus either be created from two slivers or rovings, each with or without a core yarn, or be formed from one sliver or roving and a core yarn.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.